Plasma properties of CrO x films synthesized by a cathodic arc evaporation process

Abstract

The plasma in a cathodic arc evaporation process used for the deposition of Cr 1− x O x films was studied by an optical emission spectroscopy (OES). With the introduction of Ar and oxygen into the chamber at deposition pressures from 0.7 Pa to 2.7 Pa, high density of evaporated chromium catalyzes the decomposition of oxygen reactive gas, and induces the formation of Cr 1− x O x films. Optical emission spectra including atomic and ionized Cr, excited and ionized oxygen revealed that excitation, ionization and charge transfer reactions of the Cr–O plasma occurred during the Cr 1− x O x deposition process. A simplified empirical model which incorporates the relevant atomic processes in the gas phase with the chemical composition and deposition rate of the deposited Cr 1− x O x coating was developed. Rhombohedral Cr 2O 3 and tetragonal CrO 2 were observed in the Cr 1− x O x coatings deposited at higher pressure than 1.3 Pa. The Cr 1− x O x coating depicted a dense and compact microstructure with well-attached interface.